Abstract

The response of the ATLAS calorimeters to electrons, photons and hadrons, in terms of the longitudinal and lateral shower development, is parameterized using the GEANT package and a detailed detector description (DICE). The parameterizations are implemented in the ATLAS Level-1 (LVL1) Calorimeter Trigger fast simulation package which, based on an average detector geometry, simulates the complete chain of the LVL1 calorimeter trigger system. In addition, pile-up effects due to multiple primary interactions are implemented taking into account the shape and time history of the trigger signals. An interface to the fast physics simulation package (ATLFAST) is also developed in order to perform ATLAS physics analysis, including the LVL1 trigger effects, in a consistent way. The simulation tools, the details of the parameterization and the interface are described. The LVL1 jet trigger thresholds corresponding to the current trigger menus are determined within the framework of the fast simulation, and the LVL1 jet trigger rates are estimated. Further, the combination of Et-miss signature with jet and tau triggers is also discussed. A study of the discovery potential of the ATLAS experiment of the neutral MSSM Higgs bosons in the decay channels with multi b-jet final state topologies, namely H -> h,h -> bb,bb and bb,A/H -> bb,bb, is performed. The signal acceptance of the ATLAS LVL1 jet trigger, based on the determined trigger thresholds, is evaluated. Given the dominating jet trigger rates from the QCD multi-jet processes, the b-tagging capability of the LVL2 trigger is essential for the Higgs discovery in these channels. Canonical ATLAS b-tag/mistag efficiencies are applied on reconstructed jets. Finally, 5-sigma discovery contours in the (tan(beta), mA) plane are derived.